In the field of manufacturing articles made of non-woven, paper or similar web materials, machines are used to manufacture master rolls or reels of large diameter, for example at the outlet of a web material manufacturing machine. The reels or master rolls are formed by winding the web material around a winding spindle.
The reel is then inserted in an unwinder to be unwound and to feed the web material in a substantially continuous manner to a converting line downstream.
When the reel is exhausted or almost exhausted, it must be replaced with a new reel. For this purpose, the machine is normally stopped and the spindle on which the exhausted or almost exhausted reel was wound is removed from the unwinding station and replaced with a new reel. These operations are normally managed manually. Manual execution of the changeover cycle of the exhausted reel with a new reel takes a relatively long time which cannot be estimated, as it depends very much on the operator's skill. This causes drawbacks on the conversion line downstream. For example, if an accumulator of the web material is provided between the unwinder and the rewinder, the quantity of material accumulated in the accumulator may be insufficient to continuously feed the rewinder downstream if the time to replace the exhausted reel with the new reel is longer than it should be, for example due to inexperience or lack of promptness of the operator or due to the fact that the operator must dedicate attention to more urgent operations, putting on hold or slowing down the operations to replace the exhausted reel with the new reel.
EP-A-732287 describes an automatic unwinder, in which splicing between the web material of a first almost exhausted reel and the web material of a new reel takes place when both the reels are rotating and have an identical peripheral speed. For this purpose, two unwinding members are provided, one in a first unwinding station and one in a second unwinding station. A roller is moved rapidly to perform splicing of the two web materials when the first reel is almost exhausted. This prior art device is made complex by the need to use two distinct unwinding members and a speed synchronization system to perform splicing. Moreover, it can only unwind reels wound in one direction and not reels wound in the other direction, for example only reels wound clockwise, but not counter-clockwise, or vice versa.